Looking for comments on the comparison of gain twist vs standard twist rifling. What advantage is there to gain twist? Does accuracy improve, velocity increase, pressures lower?

You can find anecdotal evidence to support just about every view on this subject.

One of the supposed advantages of gain twist is that it puts positive pressure on the leading edge interface of bullet and rifling, throughout the trip of the bullet down the bore.

One of the supposed disadvantages is that the nose of the bullet is trying to turn at a faster rate than the base of the bullet...which with long, heavy bullets may cause some "interesting" metallurgical changes...especially with bullets not enclosed within a copper or other stronger envelope. (Lead alloys "work soften".)

In cast bullet benchrest, I have seen both good results and bad results. Bev Pinney (of B.C.) won the Cast Bullet Association Grand National Championship in 1998 using one of Albertan Ron Smith's gain twist barrels chambered to .32 Miller Short. On the other hand, my Ron Smith gain-twist barrel chambered to .30 BR by Speedy Gonzalez shot very well with jacketed bullets but was a complete disaster with cast bullets.

I suspect gain twist barrels are like all others...they have individual idiosyncracies, and much depends on the skill of the maker.

One thing we do know...Harry Pope, who wasn't exactly a slouch of a barrelmaker, believed in and cut his barrels with a gain twist.

AC

[ 10-07-2003, 04:08: Message edited by: Alberta Canuck ]

I have gain twist barrels which shoot very,very well and I have uniform twist barrels which do the same. I specify a fairly moderate gain in the barrels and while it is apparent that recovered bullets have been fired in a gain twist, there is no significant deformation. The serious disruption of the bullet metal may be a possibility with a radical gain but I suspect it is more of a mental disruption than metalurgic! Regards, Bill.